Process for the production of a diene in three successive stages from a tertiary alkyl ether

Abstract

For the production of a diene a process in three stages comprisesa stage a) for decomposition of at least one tertiary alkyl ether in a mixture that contains at least one tertiary olefin, at least one alcohol and at least one residual ether, in the presence of a catalyst that comprises at least one mineral solid that is grafted by at least one organic group such as alkyl sulfonic acid, sulfonic aryl and/or sulfonic alkylaryl,a stage b) for purification of the olefin that is obtained in stage a),and a stage c) for oxidizing dehydrogenation of the tertiary olefin that is obtained in stage b) in the presence of a catalyst under conditions for obtaining a diene.

What is claimed is:  
     
       1. A process for the production of isoprene from an olefinic cut with five carbon atoms in four stages, comprising: 
       etherification of an olefinic cut with five carbon atoms in the presence of methanol or ethanol under etherification conditions to produce tert-amyl-methyl-ether (TAME) or ethyl-tert-amyl-ether (ETAE);  
       decomposition of said TAME or ETAE to a mixture containing isoamylenes, methanol or ethanol and any residual ether, in the presence of a catalyst comprising at least one mineral solid grafted by at least one organic group of an alkyl sulfonic acid, an aryl sulfonic acid or an alkylaryl sulfonic acid;  
       purification of said isoamylenes; and  
       oxidative dehydrogenation of the isoamylenes in the presence of a catalyst under conditions for obtaining isoprene.  
     
     
       2. A process according to  claim 1  in which, in said etherification, said TAME or ETAE is obtained from the reaction of said methanol or ethanol with an olefinic cut with five carbon atoms produced by fluid catalytic cracking, or by steam cracking. 
     
     
       3. A process according to  claim 1 , in which said mineral solid that is contained in the catalyst of said decomposition is a polysiloxane. 
     
     
       4. A process according to  claim 1 , in which said mineral solid that is contained in the catalyst of said decomposition is grafted by at least one alkyl sulfonic acid. 
     
     
       5. A process according to  claim 4 , wherein said at least one alkyl sulfonic acid contains 2 to 20 carbon atoms. 
     
     
       6. A process according to  claim 5 , wherein said at least one alkyl sulfonic acid contains 2 to 5 carbon atoms. 
     
     
       7. A process according to  claim 1 , in which the operating conditions of said decomposition comprise a relative pressure of between 0.1 to 3 MPa, a temperature of between 100 and 230° C., and an hourly volumetric flow rate per volume of catalyst and per hour that is between 1 and 200 h −1 . 
     
     
       8. A process according to  claim 7 , wherein the relative pressure for the decomposition stage is 0.1-1.0 MPa. 
     
     
       9. A process according to  claim 7 , wherein the temperature for the decomposition stage is 120-200° C. 
     
     
       10. A process according to  claim 9 , wherein L.S.H.V. for the decomposition stage is about 2-50. 
     
     
       11. A process according to  claim 9 , wherein L.S.H.V. for the decomposition stage is about 2-20. 
     
     
       12. A process according to  claim 7 , wherein the hourly volumetric flow rate per volume of catalyst and per hour for the decomposition stage is 1-100 h −1 . 
     
     
       13. A process according to  claim 1 , in which the purification of the isoamylenes comprises at least one washing with water and at least one distillation, whereby the washing and the distillation are carried out in any order. 
     
     
       14. A process according to  claim 13 , wherein the operating conditions of the washing with water in said purification comprise the use of water in a volumetric ratio with the mixture that is obtained in said decomposition from about 0.005 to 100, a temperature from about 1 to 100° C. and an absolute pressure from about 0.1 to 2 MPa, and the operating conditions of the distillation in said purification comprise a pressure in the distillation column from about 0.1 to 1.5 MPa, identical to or different from that of the washing, whereby said column comprises a number of plates of between 3 and 80 theoretical plates. 
     
     
       15. A process according to  claim 14 , wherein the volumetric ratio for the washing with water is about 0.01-20. 
     
     
       16. A process according to  claim 14 , wherein the volumetric ratio for the washing with water is about 0.1-10. 
     
     
       17. A process according to  claim 14 , wherein the volumetric ratio for the washing with water is about 0.5-5. 
     
     
       18. A process according to  claim 14 , wherein the temperature of a plate column is 10-60° C. 
     
     
       19. A process according to  claim 14 , wherein the absolute pressure for the washing with water is about 0.1-1.5 MPa. 
     
     
       20. A process according to  claim 14 , wherein the pressure in the distillation column for the washing with water is 0.2-1 MPa and the number of theoretical plates is 10-50. 
     
     
       21. A process according to  claim 1 , in which the purification of the isoamylenes comprises a washing with water of the mixture that is obtained from said decomposition so as to obtain an isoamylene-rich organic phase that contains isoamylene, unconverted TAME or ETAE and a methanol- or an ethanol-rich aqueous phase, followed by the distillation of the organic phase to recover the isoamylene and the unconverted TAME or ETAE. 
     
     
       22. A process according to  claim 21 , in which the water of the methanol or ethanol-rich aqueous phase that is obtained from said purification is separated from methanol or ethanol and then recycled to said purification. 
     
     
       23. A process according to  claim 1 , in which the catalyst of said oxidative dehydrogenation comprises at least one metal oxide of Co, Ni, Mo, W or an alkaline metal, on a substrate of alumina, silica or silica-alumina. 
     
     
       24. A process according to  claim 1 , which the operating conditions of said oxidative dehydration comprise a partial hydrocarbon pressure of between 10 4  and 5.10 5  Pa, a temperature of between 450 and 700° C. and a feedstock weight/catalyst weight/hour of between 0.1 and 5 h −1 . 
     
     
       25. A process according to  claim 24 , in which the catalyst of said oxidative dehydrogenation consists essentially of at least one metal oxide of Co, Ni, Mo, W or an alkaline metal, on a substrate of alumina, silica or silica-alumina. 
     
     
       26. A process according to  claim 24 , in which the catalyst of said oxidative dehydrogenation consists of at least one metal oxide of Co, Ni, Mo, W or an alkaline metal, on a substrate of alumina, silica or silica-alumina. 
     
     
       27. A process according to  claim 1 , wherein the isoprene is obtained by converting at least about 70% of the isoamylenes in a single pass with a selectivity of isoprene of at least about 68%. 
     
     
       28. A process according to  claim 1 , in which the operating conditions of said decomposition comprise a relative pressure of between 0.1-1 MPa, a temperature of 120-200° C., and an hourly volumetric flow rate per volume of catalyst and per hour that is 2-50 h −1 . 
     
     
       29. A process according to  claim 1 , in which the operating conditions of said oxidative dehydrogenation comprise a partial hydrocarbon pressure of 10 4  -2.10 5  Pa, a temperature of 600-680° C. and a feedstock weight/catalyst weight/hour of 0.5-2 h −1 . 
     
     
       30. A process according to  claim 1 , wherein said organic group is an alkyl sulfonic acid containing 1 to 24 carbon atoms, an aryl sulfonic acid containing 6 to 18 carbon atoms, or an alkylaryl sulfonic acid containing 7 to 24 carbon atoms. 
     
     
       31. A process for the production of isoprene from an olefinic cut with five carbon atoms in four stages, comprising: 
       etherification of an olefinic cut with five carbon atoms in the presence of methanol or ethanol under etherification conditions to produce tert-amyl-methyl-ether (TAME) or ethyl-tert-amyl-ether (ETAE);  
       decomposition of said TAME or ETAB to a mixture containing isoamylenes, methanol or ethanol and any residual ether, in the presence of a catalyst comprising at least one mineral solid grafted by at least one organic group of an alkyl sulfonic acid, an aryl sulfonic acid or an alkylaryl sulfonic acid wherein said mineral solid that is contained in the catalyst of said decomposition is grafted by at least one alkyl sulfonic acid and the catalyst of said decomposition comprises at least one unit of formula (I) below:  
       
         
           (O {fraction (3/2)} Si-R 1 -SO 3   − )H +   (I)  
         
       
       where R 1  is an alkyl radical; 
       purification of said isoamylenes; and  
       oxidative dehydrogenation of the isoamylenes in the presence of a catalyst under conditions for obtaining isoprene.  
     
     
       32. A process for the production of isoprene from an olefinic cut with five carbon atoms in four stages, comprising: 
       etherification of an olefinic cut with five carbon atoms in the presence of methanol or ethanol under etherification conditions to produce tert-amyl-methyl-ether (TAME) or ethyl-tert-amyl-ether (ETAE);  
       decomposition of said TAME or ETAE to a mixture containing isoamylenes, methanol or ethanol and any residual ether, in the presence of a catalyst comprising at least one mineral solid grafted by at least one organic group of an alkyl sulfonic acid, an aryl sulfonic acid or an alkylaryl sulfonic acid wherein said mineral solid that is contained in the catalyst of said decomposition is grafted by at least one alkyl sulfonic acid and in which said catalyst of said decomposition contains a polymeric unit of the formula:                    
       purification of said isoamylenes; and  
       oxidative dehydrogenation of the isoamylenes in the presence of a catalyst under conditions for obtaining isoprene.  
     
     
       33. A process for the production of isoprene from an olefinic cut with five carbon atoms in four stages, comprising: 
       etherification of an olefinic cut with five carbon atoms in the presence of methanol or ethanol under etherification conditions to produce tert-amyl-methyl-ether (TAME) or ethyl-tert-amyl-ether (ETAB);  
       decomposition of said TAME or ETAE to a mixture containing isoamylenes, methanol or ethanol and any residual ether, in the presence of a catalyst comprising at least one mineral solid grafted by at least one organic group of an alkyl sulfonic acid, an aryl sulfonic acid or an alkylaryl sulfonic acid;  
       purification of said isoamylenes; and  
       oxidative dehydrogenation of the isoamylenes in the presence of a catalyst comprising at least one metal oxide of Co, Ni, Mo, W or an alkali metal, on a substrate of alumina, silica or silica-alumina under conditions comprising a partial hydrocarbon pressure of between 10 4  and 5.10 5  Pa, a temperature of between 450 and 700° C. and a feedstock weight/catalyst weight/hour of between 0.1 and 5 h −1  for obtaining isoprene.  
     
     
       34. A process for the production of isoprene from an olefinic cut with five carbon atoms in four stages, comprising: 
       etherification of an olefinic cut with five carbon atoms in the presence of methanol or ethanol under etherification conditions to produce tert-amyl-methyl-ether (TAME) or ethyl-tert-amyl-ether (ETAE) wherein said TAME or ETAE is obtained from the reaction of said methanol or ethanol with an olefinic cut with five carbon atoms produced by fluid catalytic cracking or by steam cracking;  
       decomposition of said TAME or ETAE to a mixture containing isoamylenes, methanol or ethanol and any residual ether, in the presence of a catalyst comprising at least one mineral solid grafted by at least one organic group of an alkyl sulfonic acid, an aryl sulfonic acid or an alkylaryl sulfonic acid wherein the operating conditions of said decomposition comprise a relative pressure of between 0.1 to 3 MPa, a temperature of between 100 and 230° C., and an hourly volumetric flow rate per volume of catalyst and per hour that is between 1 and 200 h −1 ;  
       purification of said isoamylenes; in which the purification of the isoamylenes comprises at least one washing with water and at least one distillation, whereby the washing and the distillation are carried out in any order, and wherein the operating conditions of the washing with water in said purification comprise the use of water in a volumetric ratio with the mixture that is obtained in said decomposition from about 0.005 to 100, a temperature from about 1 to 100° C. and an absolute pressure from about 0.1 to 2 MPa, and the operating conditions of the distillation in said purification comprise a pressure in the distillation column from about 0.1 to 1.5 MPa, identical to or different from that of the washing, whereby said column comprises a number of plates of between 3 and 80 theoretical plates, and oxidative dehydrogenation of the isoamylenes in the presence of a catalyst comprising at least one metal oxide of Co, Ni, Mo, W or an alkaline metal, on a substrate of alumina, silica or silica-alumina under conditions comprising a partial hydrocarbon pressure of between 10 4  and 5.10 5  Pa, a temperature of between 450 and 700° C. and a feedstock weight/catalyst weight/hour of between 0.1 and 5 h −1  for obtaining isoprene.